Process of making caustic alkalies.



WILLIAM T. GIBBS, OF BUCKIXGHAM, QUEBEC, CANADiL PROCESS OF MAKINGSpecification of Letters Patent.

CAUBTIC ALKALXES.

Patented Jan. 26, 1909.

Application filed March 10, 1906. Serial No. 305,331.

To all whom it may concern: f Be it known that I, \VILLIAM TAYLOR GIBBS,a subject of the King of (ireat Britain and Canada, residing atBucltingham. Province of Quebec, county of Ottawa. ('anada,

have invented certain new and useful improvements in Processes of Ma'ingCaustic Alkalies, fully descriled and represented in the followingspecification.

This invention relates to a new method of making caustic alkalies Lydecomposing or breaking up refractory silicates-such, for instance, asthe feldspars, potashorlithia micas and the like, and recovering thealkalies coul 5 tained therein. l

I have discovered that by digesting the: finely powdered silicate with asuitable alkal line earth hydrate under suitable pressure, l thesilicate may he decomposed, the alkaliesgoing into solution in the waterpresent as 1 hydrates. The alkaline earth hydrate that I r referably useis milk of lime. but other all'ai ine earth hydrates such, for instance,as h l drated oxid of barium. strontium or Inagne- 5 sium. may be used.The lrest results in ohtaining aikalies will he secured h using the limeor other alkaline earth in the proportion of two molecules of hydratedcalcium or other oxid {or every molecule of silica and one molecu e foreach molecule of alumina present, in the silicate which it is desired todecompose, but these proportions may be! varied. In carrying out therocess in practice, the silicates are iulverizet so as to he treated in1 a finely divided state. then mixed with milk 3 of lime or the otheralkaline earth hvdra-te 1 used. and digested under pressure, preferablysteam pressure. I find a convenient steam i 0 pressure to be between 125and 150 pounds l per square inch above the atmosphere, but l I thesilicates are ground.

any pressure desired may be used,so long as it is high enough to securesuch a digesting temperature as to cause the reaction to take placeithin a reasonable time. With the pressure stated, the reaction will becompleted in from twelve to twenty-four hours, depending upon thecharacter of the silicate under treatment, and the fineness to which Forrecovering the all-ialies after decomposition of the silicates, theresulting sludge is filtered and the residual mud washed until free fromalkali. The first filtrate and the sul. sequent washings are evaporatedto any desired strength of caustic, or. by evaporating and fusing theresidue, solid caustic alka is obtained on cooling.

It will be seen that by this process the alkalies are obtained in theirmost valuable commercial form, that is, as hydrates, caustic potashbeing produced by treating potash feldspar, caustic soda b treatingsoda. feldspar, and lithium hydrate Jy treating refractory silicatescontaining lithium, etc.

What I claim is:

1. The process of making caustic alkalies, which consists in digestingfinel divided refractory silicates containing alka ies with a. solutionof an alkaline earth hydrate under pressure.

2. The process of making caustic alkalies, which consists in di estinfinely divided potash feldspar 1th milk of ime under steam pressure. 75

In testimon whereof, I have hereunto setmy hand, in t to presence of twosutscribing vntnesses.

WILLIAM T. GIBBS. \Yitnesses A. WHITE, (3. J. SAWYEB.

